The high-pressure transfer device according to the invention contains many features in common with that in the copending application Ser. No. 209,118 filed Nov. 21, 1980, now U.S. Pat. No. 4,430,029--the disclosure of which is hereby incorporated by reference herein--such as minimizing leakage that may come about as a result of radial deflection of the housing, accommodating a large amount of wear of the operative components before replacement, etc. The device according to the present invention is, however, more particularly applicable to the transfer of wood chips, and the like, although it is also useful in the transfer of coal, oil shale, and like hard particulate material.
The basic features of the high-pressure transfer device according to the invention include a cylindrical pocketed rotor, a housing enclosing the rotor and having low-pressure inlet and outlet ports, and high-pressure inlet and outlet ports, means for mounting the rotor for rotation with respect to the housing, screen means for screening particulate material above a predetermined size out of the liquid, and sealing means disposed in a large clearance volume between the rotor and housing for maintaining effective sealing between the rotor and housing. The sealing means preferably comprises a low-pressure inlet shoe, a low-pressure outlet shoe, a high-pressure inlet shoe, and a high-pressure outlet shoe.
According to the present invention, particular retainer means are associated with the shoes for guiding the radial movement thereof, and prevent rotation of the shoes with respect to the housing. The retainer means preferably takes the form of a retainer associated with each of the low-pressure inlet and low-pressure outlet. The retainers each comprise a portion including side wall portions which engage side walls of the low-pressure shoes, and end wall portions--generally transverse to the side wall portions--engaging side walls of the high-pressure shoes. Preferably the low-pressure inlet and outlet ports are quadrate (square or rectangular) in cross-section, as are the low-pressure inlet and outlet shoes, and the retainers.
High-pressure compensators are associated with the high-pressure shoes and supplied with hydraulic fluid to maintain a biasing force proportional to the pressure in the high-pressure inlet and outlet. One pressure compensator surrounds each of the high-pressure inlet and outlet ports. The openings in the high-pressure shoes which cooperate with the high-pressure inlet and outlet ports, respectively, may be cylindrical, or they may be circular in cross-section at the portions thereof most remote from the rotor, and taper to be quadrate (e.g. square) in cross-section at the portions thereof closest the rotor. This facilitates the utilization of a quadrate pocket mouth, which is especially desirable for cooperation with the quadrate low-pressure inlet and outlet ports.
The housing is allowed to deflect radially under heavy pressure loads since the shoes will accommodate housing deflection without undesired leakage. The housing may be formed by a plurality of axially extending ribs disposed around the periphery thereof, and joined at the ends by radially extending ribs.
It is the primary object of the present invention to provide an effective high-pressure transfer device for use with wood chips, particulate material, and the like. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.